Data Collection: Agonistic Display in Betta splendens

Transcription

1 Data Collection: Agonistic Display in Betta splendens You should now be well-versed in observing the various aspects of the agonistic display of male Betta splendens. Your team should now be ready to collect data for your carefully designed experiment. I. Betta splendens Research: Observations and Hypotheses In designing your experiment, consider the following questions, as well as others your team has posed. What are the possible functions of agonistic display in male Betta splendens? How might certain aspects of the display behavior been adaptive in the wild ancestors of these fish? Why do males bother with display? Why not just launch into battle? Wild Betta splendens are not as brightly colored, and do not have fins as long and showy as the domestic variety you are observing. How might artificial selection have affected the behavior of these fish? Do you think some or all of your results can be applied to wild populations? Which ones, if any, and why? What other environmental factors might affect the agonistic display of Betta splendens? Of what evolutionary and/or ecological significance are these factors? Now that your team has decided on an experimental question based on your previous observation of Betta splendens behavior, complete the following. Observation: List as many explanations as possible for this observation: Overall Hypothesis: Null Hypothesis: Alternative Hypothesis: Prediction:

2 What parameter(s) will you record/measure? How many replicates will you perform? Describe your experimental methods: What statistical test will you employ to analyze your results, and why is it appropriate? You may use the data forms on the following pages to record data, or use a spreadsheet of your own design. Whichever you choose to use, be sure to accurately record all data. Remember that there is no right answer, and it is unwise to assume that your prediction is correct. The reason you are performing these experiments is to reject or fail to reject your experimental hypotheses, not to prove that your hypotheses are correct.

3 Table 2. Ethogram for Betta splendens Behavior Description of behavior

4 Table 3. Behavioral observations of Betta splendens during a five-minute period Behavior: 0:15 0:30 0:45 1:00 1:15 1:30 1:45 2:00 2:15 2:30 2:45 3:00 3:15 3:30 3:45 4:00 4:15 4:30 4:45 5:00 Total Notes

5 II. Review: General Instructions 1. Some individual fish are particularly sensitive or aggressive, and these may be stimulated even by the sight of brightly colored or patterned clothing. Avoid wearing such clothing to lab. Pale-colored clothing is the least likely to interfere with fish behavior. 2. Position your fish where it cannot see neighboring animals until you are ready to begin your experiment. Keep the visual barriers in place unless you are actually making observations of fish behavior. 3. Avoid abrupt movements when near the fish, and speak quietly. Do not tap on the side of the fish bowl, as this creates a very loud, stressful noise for the fish. 4. When recording the positions and movements of your Betta's display, note that the male will employ most of its fins, its gill opercula, and the associated branchiostegal membrane. A particularly energetic male may bend his body in tight angles. Note the orientation of the fish to its stimulus and record any changes in the coloration of your fish (for example, watch for color to fade or become brighter, or for color streaks to appear on various areas of the body. 5. Be sure to record the length of time of each behavior you are recording, as well as its subjective aspects (for example, you might rate the strength of the display ("-" for weak, "+" for medium, "++" for strong or variations on that theme, perhaps using numbers to rank degree of energy shown by the fish.) Do not stimulate the fish for longer than one minute for each trial, as longer trials may result in habituation to the stimulus. 6. Wait least 5 minutes between trials, allowing the fish to calm down completely. Between trials, be sure to block your subject's view of other fish, and avoid fast movements or loud noises. (Sound travels much more easily through water than through air. So don t say anything rude about the fish. They can hear you.) 7. It may be helpful to record the sequence of movements the fish uses in a full display. 8. Replicate each trial at least 3 times. Note any differences between replicates. What might cause such differences as time goes on? 9. Paper fish models will also elicit a response from males, but because they are stationery, they might not elicit as strong a response. However, the subject will also not habituate as quickly to a static model as to a mirror (why might this be the case?) 10. When using a paper model, move it slowly up to the subject and then wave it slightly to attract the subject's attention. Try to use similar technique and movement in each trial, to avoid introducing human error into your experiment. 11. Male Bettas will respond strongly to the sight of another member of its own species, whether male or female. Consider the responses of your fish to same sex or different sex stimulus. 12. Refer to the fish anatomy diagram in the previous week s lab chapter when designing your ethogram. IV. Ethical Treatment of Experimental Subjects Be kind to your fish, and we will be kind to you. Any student witnessed abusing animals in the laboratory will be immediately dismissed from the lab, receive a ZERO on the lab project and presentation, and be subject to possible additional disciplinary action.

6 Animals of any species used in experimental studies should always be treated with respect, and given the proper care and maintenance at all times. Adopt-a-Fish! The fish being used in your project will be available for adoption after all the experiments have been completed. If you would like to adopt a Betta splendens for your very own, you will need the following: 1. an appropriate vessel (minimum 2.5 gallons) 2. good-quality food (Spectrum brand is the best) 3. dechlorination solution (essential!) 4. floating live plants (provides cover, comfort, and oxygen) 5. a bit of gravel for the bottom of the bowl 6. a small vessel (e.g., a plastic bowl with a lid) to bring your fish home. Note that even females will fight and bully one another if they do not have sufficient space to avoid each other, so unless you have a very large, community tank, you must have a separate vessel and supplies for each fish you adopt. Also note that as aggressive as these fish are to each other they are relatively docile when confronted with aggression from other species. If you have a community tank with aggressive species (e.g., Tiger barbs, cichlids, etc.), it is best to keep your Betta in a separate environment. Betta splendens is beautiful and relatively easy to keep, but this species does require specific care. Please read about care information before you adopt: Please contact Dr. Dana Krempels (dana@miami.edu) or ask your laboratory instructor for more information about adopting a fish at the end of the semester.